Vibrotactile Encoding of Object Features and Alert Levels for the Visually Impaired

Representation of object features can help visually impaired people better comprehend their surrounding environment. Tacton (Tactile Icon) is an effective method to extract and express information non-visually, utilizing users' tactile perception capacities. However existing vibrotactile displays mainly place emphasis on directional guidance, and the number of representable object features is very limited. To leverage the egocentric spatial cognition habit and high tactile perception sensitivity of visually impaired users, this research proposes a usercentered vibrotactile cueing strategy to convey 30 kinds of spatial information through 30 tactons played by 4 vibrators on the back and front side of a pair of gloves. Three parameters including vibration sequence, stimulus location, and intensity are used to encode 10 typical objects located in 3 directions with 2 alert levels. User tests in both laboratory and natural settings are conducted to evaluate the validity of the strategy. The recognition accuracy of the designed tacton has reached 98.99% within a recognition time of less than 0.6s, indicating that this strategy can provide practical assistance for visually impaired users to perceive and respond to the pre-defined spatial information. The multi-parameter tactons provide possibility to encode a wide variety of spatial information by exploiting the communication capacities of the tactile channel of visually impaired users.